Removed DB specific get api's from Selectable class (#378)

* Address Review comments
#376
to remove DB specific API from selectable class
which is generic.

However to access to the Derviced Class Redis Select
API via python we need to downcast the the Selectable Object.

Added Helpfer function to do same.

Ref: http://www.swig.org/Doc3.0/Python.html

Signed-off-by: Abhishek Dosi <[email protected]>

* Align the code properly

Signed-off-by: Abhishek Dosi <[email protected]>

* Address Review Comments. Return the DBConnector Pointer.
Since the DBConnector is unique_ptr return the
reference to the contained object, or a non owning pointer

Signed-off-by: Abhishek Dosi <[email protected]>

Author: abdosi

common/redisselect.cpp

@@ -16,14 +16,10 @@ int RedisSelect::getFd()
 {
     return m_subscribe->getContext()->fd;
 }
-int RedisSelect::getDbConnectorId()
-{
-    return m_subscribe->getDbId();
-}
 
-std::string RedisSelect::getDbNamespace()
+const DBConnector* RedisSelect::getDbConnector() const
 {
-    return m_subscribe->getNamespace();
+    return m_subscribe.get();
 }
 
 uint64_t RedisSelect::readData()

common/redisselect.h

@@ -20,8 +20,7 @@ class RedisSelect : public Selectable
     bool hasCachedData() override;
     bool initializedWithData() override;
     void updateAfterRead() override;
-    int getDbConnectorId() override;
-    std::string getDbNamespace() override;
+    const DBConnector* getDbConnector() const;
 
     /* Create a new redisContext, SELECT DB and SUBSCRIBE */
     void subscribe(DBConnector* db, const std::string &channelName);

common/selectable.h

@@ -58,16 +58,6 @@ class Selectable
         return m_priority;
     }
 
-    virtual int getDbConnectorId()
-    {
-        return 0;
-    }
-
-    virtual std::string getDbNamespace()
-    {
-        return std::string();
-    }
-
 private:
 
     friend class Select;

pyext/swsscommon.i

@@ -35,6 +35,7 @@
 %typemap(in, numinputs=0) swss::Selectable ** (swss::Selectable *temp) {
     $1 = &temp;
 }
+
 %typemap(argout) swss::Selectable ** {
     PyObject* temp = NULL;
     if (!PyList_Check($result)) {
@@ -45,6 +46,13 @@
     temp = SWIG_NewPointerObj(*$1, SWIGTYPE_p_swss__Selectable, 0);
     SWIG_Python_AppendOutput($result, temp);
 }
+
+%inline %{
+swss::RedisSelect *CastSelectableToRedisSelectObj(swss::Selectable *temp) {
+  return dynamic_cast<swss::RedisSelect *>(temp);
+}
+%}
+
 %include "schema.h"
 %include "dbconnector.h"
 %include "selectable.h"